Mutations Linked to Blood Cancer Surprisingly High in Older People

Researchers have found that at least 2 percent of people over 40, as well as 5 percent of people over 70, have genetic mutations linked to leukemia and lymphoma.

The findings, from investigators at Washington University School of Medicine, don’t mean that people with the mutations are destined to get blood cancer. The incidence of leukemia and lymphoma is less than 0.1 percent among elderly people.

“But it’s quite striking how many people over age 70 have these mutations,” said senior author Li Ding, PhD, of The Genome Institute at Washington University. “The power of this study lies in the large number of people we screened.”

In the study, published in the journal Nature Medicine, the researchers analyzed blood samples from participants in The Cancer Genome Atlas project. The federally funded project is aimed at identifying genetic errors involved in more than 20 types of cancers.

The participants whose blood was analyzed in the current study had been diagnosed with cancer but not with leukemia, lymphoma or any blood disease. Because the subjects donated blood before beginning chemotherapy or radiation, there was no way that the cancer treatment influenced the findings. Chemotherapy and radiation can damage cellular DNA.

After looking at the samples, the researchers determined that in 341 patients ages 40-49, fewer than 1 percent had mutations in 19 leukemia- or lymphoma-related genes. But among 475 people ages 70-79, more than 5 percent did, while over 6 percent of the 132 people ages 80-89 had the mutations.

The presence of the mutations may be a precursor to the illnesses, but only in a small number of patients. The study, researchers said, was not aimed at predicting future risk. They also said that the findings don’t mean that people should be genetically screened for their risk of leukemia or lymphoma. “We would not want anyone to think they should be screened for these mutations to understand their risk of leukemia or lymphoma,” said co-author and
leukemia scientist Timothy Ley, MD, the Lewis T. and Rosalind B. Apple Professor of Oncology. “The ability to understand how mutations in these genes increase a person’s risk of blood cancers is a long way off, and genetic testing would be of no benefit at this time.”